Stannane Gas Supply System

ABSTRACT

To provide a stannane gas supply system capable of supplying a stannane gas to an extreme ultraviolet ray radiation source with a stable flow rate. A stannane gas supply system for supplying a stannane gas to an extreme ultraviolet ray radiation source characterized by comprising a sealed container for storing a mixture of a stannane liquid and a stannane gas, connected with the extreme ultraviolet ray radiation source via a pipe, cooling means for cooling the sealed container to a temperature lower than −60° C., a low pressure mass flow controller provided in the pipe, a pressure detecting device mounted in the pipe part disposed between the sealed container and the low pressure mass flow controller, for detecting the pressure of the stannane gas in the pipe part, and controlling means for controlling the cooling degree of the sealed container by the cooling means based on the pressure detection value by the pressure detecting device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 (a) and (b) to Japanese Application No. JP 2006-222191, filed Aug. 17, 2006, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a stannane gas supply system for supplying a stannane (monostannane [SnH₄]) gas to an extreme ultraviolet ray radiation source.

BACKGROUND ART

A stannane (monostannane [SnH₄]) gas has been attracting attention as a gas component for an extreme ultraviolet ray radiation source of an exposing device which performs lithography by radiating an extreme ultraviolet ray in a process for producing a semiconductor device (see Japanese Patent Application No. 2004-279246). In the application of the stannane gas to such an extreme ultraviolet ray radiation source, in order to stably radiate the extreme ultraviolet ray from the radiation source, it is necessary to supply the stannane gas to the extreme ultraviolet ray radiation source with a stable flow rate.

However, since the stannane is extremely unstable (for example, it is decomposed rapidly in the room temperature) and highly toxic, its handling is extremely difficult.

For these reasons, Japanese Patent Publication No. 60-42203 discloses a method for stabilizing the stannane for stably storing the stannane by pouring the stannane in a container and maintaining the container temperature at −150° C. to −50° C. However, JP 60-42203 has no disclosure on the technique for supplying the stannane filled in the container with a stable flow rate in the gas state.

Problem to Be Solved

An object of the present invention is to provide a stannane gas supply system capable of supplying a stannane gas to an extreme ultraviolet ray radiation source with a stable flow rate.

Means for Solving the Problem

According to the present invention, there is provided a stannane gas supply system which supplies a stannane gas to an extreme ultraviolet ray radiation source, characterized by comprising:

-   -   a sealed container which stores a mixture of a stannane liquid         and a stannane gas, connected with the extreme ultraviolet ray         radiation source via a pipe;     -   cooling means for cooling the sealed container to a temperature         lower than −60° C.;     -   a low pressure mass flow controller provided in the pipe;     -   a pressure detecting device which is mounted in the pipe part         disposed between the sealed container and the low pressure mass         flow controller, and which detects the pressure of the stannane         gas in the pipe part; and     -   controlling means for controlling the cooling degree of the         sealed container by the cooling means based on the pressure         detection value by the pressure detecting device.

ADVANTAGES OF THE INVENTION

According to the present invention, a stannane gas supply system capable of supplying a stannane gas to an extreme ultraviolet ray radiation source with a stable flow rate and stably radiating the extreme ultraviolet ray from the radiation source can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the stannane gas supply system according to embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic chart showing a stannane gas supply system according to a first embodiment.

A sealed container for storing a mixture of a stannane (monostannane [SnH₄]) liquid and a stannane (monostannane [SnH₄]) gas, for example, a tank I is stored in a inside housing 2 with its upper side opened. The inside housing 2 is stored in an outside housing 4 having an exhaust pipe 3 in the upper part thereof. The tank 1 is connected with a stannane gas supply line L1 for supplying a stannane gas to an extreme ultraviolet ray radiation source 41. The supply line L1 part disposed outside the outside housing 4 has a low pressure mass flow controller LMSFC capable of controlling the flow rate in a pressure range of 50 to 300 Torr and a switching valve V1 provided from the tank 1 side. The supply line L1 part inside the outside housing 4 between the tank 1 and the low pressure mass flow controller LMSFC is provided with a pressure detecting device 5 for detecting the pressure of the stannane gas passing in the supply line L1.

A freezing device 11 serving as cooling means for cooling the tank 1 to a temperature lower than −60° C. comprises a coolant circulation line L2 passing through the outside housing 4 and inside housing 2 and having a winding part 12 winding around the tank 1 at the through part to function as an evaporating device. The circulation line L2 is provided with a compressing device 13, a condensing device 14 and an expansion valve 15 from the winding part 12 side along the coolant flow direction successively. The freezing device 11 cools down the stannane in the tank 1 to a certain temperature at the winding part 12 functioning as an evaporating device.

A heating gas (for example a room temperature air) supply system 21 for supplying a gas higher than the cooling temperature of the tank 1 by the freezing device 11 comprises a room temperature air supply line L3 for supplying the room temperature air inserted into the inside housing 2 through the outside housing 4. The portion of the room temperature air supply line L3 disposed in the outside housing 4 is provided with a control valve Vc1 to have the total closure or opening degree adjustment by a control signal from a controlling device to be described later. According to the room temperature air supply system 21, by the opening degree adjustment of the control valve Vc1, the room temperature air supply amount to the inside housing 2 storing the tank 1 is controlled so that the stannane in the tank 1 is heated according to the room temperature air supply amount. The heating gas is not limited to the air, and a rare gas such as nitrogen and argon can be used.

A controlling device 6 disposed inside the outside housing 4 has a pressure detection value signal inputted from the pressure detecting device 3. The controlling device 6 compares the inputted pressure detection value signal with a set pressure (for example 50 to 300 Torr). In the case the pressure detection value signal is off the set pressure, the comparison result is outputted to the control valve Vc1 of the room temperature gas supply system 21 as a control signal so as to adjust the opening degree thereof. That is, supply stoppage of the heating gas (for example the room temperature air) to the housing 2 and the supply amount control are carried out.

The controlling device 6 and the room temperature supply system 21 constitute a controlling means.

As mentioned above, since the stannane gas used for the stannane gas supply system according to the first embodiment is a highly decomposable gas, decomposition and explosion by the excessive decomposition are avoided by keeping the gas at a low temperature (for example −60° C. or lower). Moreover, the temperature of the stannane liquid and the pressure of the stannane liquid have an exponentially proportional relationship. That is, in the tank 1 for storing the stannane liquid and gas, if the temperature of the stannane liquid in the tank 1 is lowered, the pressure of the stannane gas to be supplied from the tank 1 to the supply line L1 is lowered as well. If the temperature of the stannane liquid in the tank 1 is raised, the pressure of the stannane gas to be supplied from the tank 1 to the supply line L1 is raised as well. Furthermore, the present inventors have found that at the time of cooling down the stannane in the tank 1 by the freezing device 11 in the tank 1 for storing the mixture of the stannane liquid and the stannane gas, the stannane is cooled down by the vaporization heat generated at the time of vaporizing the stannane liquid in addition to the cooling operation so that the pressure of the stannane gas supplied to the supply line L1 for flowing is lowered.

On the other hand, according to the mass flow controller for the flow rate control of a gas, in general even though the flow rate control of a gas on the higher pressure side than the atmospheric pressure (760 Torr) is easy, a gas on the lower pressure side is dealt with using a low pressure mass flow controller. However, according to a stannane gas supply system to be handled at a low temperature (for example −60° C. or lower), even though the low pressure mass flow controller is used, due to the temperature decline of the stannane liquid in the tank 1 and the reduction of the pressure of the stannane gas supplied to the supply line L1 accompanied thereby, it may be lower than the pressure range of the flow rate to be controlled by the low pressure mass flow controller.

In the stannane gas supply system in which the fluctuation (in particular, the pressure decline) of the pressure of the stannane gas to be supplied occurs, by carrying out the temperature control of the tank 1 (mainly the stannane liquid) by the pressure detecting device 5 and the controlling means (comprising the controlling device 6 and the room temperature air supply system 21 having the control valve Vc1), that is, the pressure control of the stannane gas supplied from the tank 1, the pressure of the stannane gas to be supplied to the stannane gas supply line L1 so as to flow can be provided in a pressure range to enable the flow rate control of the low pressure mass flow controller LMSFC, for example, 50 to 300 Torr so that the stannane gas flowing in the supply line L1 can be supplied to the extreme ultraviolet ray radiation source 41 with the precise adjustment to the targeted flow rate by the low pressure mass flow controller LMSFC.

The operation of the stannane gas supply system having such a control system and the configuration shown in FIG. 1 according to the first embodiment will be explained specifically.

The tank 1 storing a mixture of the stannane liquid and the stannane gas preliminarily cooled down (for example −80° C.) is set in the housing 2. Immediately, the tank 1 is cooled down to a temperature lower than −60° C. by the freezing cycle of the freezing device 11 (for example to −80° C.). That is, by driving the compressing device 13 of the freezing device 11, the coolant in the circulation line L2 is compressed. The compressed high pressure coolant is introduced into the condensing device 14 through the circulation line L2 so as to have the thermal exchange for being condensed and liquefied. The liquefied coolant is introduced to the expansion valve 15 through the circulation line L2 so as to be expanded here for lowering the pressure for facilitating evaporation in the circulation winding part 12 as the evaporating device on the downstream side. The liquefied coolant with the pressure lowered is vaporized at the winding part 12 of the circulation line L2 as the evaporating device so as to cool down the tank 1 by its vaporization heat. According to the freezing cycle of the coolant of the freezing device 11, the mixture of the stannane liquid and the stannane gas in the tank 1 is cooled down to a temperature lower than −60° C. (for example −80° C.) so as to complete the supply preparation of the stannane gas to the extreme ultraviolet ray radiation source 41.

By opening the valve of the tank 1 and the switching valve V1 of the stannane gas supply line L1, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 through the supply line L1. At this time, the pressure of the stannane gas flowing in the supply line L1 is detected by the pressure detecting device 5. In the case the signal of the pressure detection value is in the range of the set pressure of the controlling device 6 (for example 50 to 300 Torr), the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 through the supply line L1 without outputting the control signal from the controlling device 6 to the control valve Vc1 of the room temperature air supply system 21, that is, without the cooling control of the tank 1 serving as the stannane gas supply source. That is, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC capable of controlling the flow rate in the pressure range of 50 to 300 Torr, the LMSFC being provided in the supply line L1. By operating the extreme ultraviolet ray radiation source 41 in this state, the extreme ultraviolet ray can be radiated stably from the radiation source 41.

In the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is outside the set pressure (for example 50 to 300 Torr), that is, for example a detection signal less than the lower limit of the set pressure is outputted from the pressure detecting device 5 to the controlling device 6 by cooling accompanied by the vaporization of the stannane liquid in the tank 1 as mentioned above, a control signal is outputted from the controlling device 6 to the control valve Vc1 of the room temperature air supply system 21 so as to perform the opening degree adjustment of the control valve Vc1 according to the control signal. According to the opening degree adjustment of the control valve Vc1, the room temperature air is supplied into the inside housing 2 through the room temperature air supply line L3 so as to heat the tank 1 (mainly the stannane liquid). By heating the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is raised so as to be controlled into the set pressure of the controlling device 4, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSF. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

On the other hand, in the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is higher than the upper limit of the set pressure (for example 50 to 300 Torr), a signal for closing the control valve Vc1 of the room temperature air supply system 21 is outputted through the controlling device 6 so as to stop the room temperature air supply to the inside housing 2 from the room temperature air supply line L3. That is, the tank 1 (mainly the stannane liquid) is cooled down by the freezing device 11. By cooling down the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is lowered so as to be controlled into the set pressure of the controlling device 4, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSF. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

Therefore, according to the first embodiment, in the stannane gas supply system for supplying a stannane gas cooled down to a stable temperature without decomposition to the extreme ultraviolet ray radiation source 41, by carrying out the temperature control of the tank 1 (mainly the stannane liquid) by the pressure detecting device 5 and the controlling means (comprising the controlling device 6 and the room temperature air supply system 21 having the control valve Vc1), that is, the pressure control of the stannane gas supplied from the tank 1, the pressure of the stannane gas to be supplied to the stannane gas supply line L1 so as to flow can be provided in a pressure range to enable the flow rate control of the low pressure mass flow controller LMSFC, for example, 50 to 300 Torr. Therefore, the stannane gas flowing in the supply line L1 can be supplied to the extreme ultraviolet ray radiation source 41 with the precise adjustment to the targeted flow rate by the low pressure mass flow controller LMSFC. As a result, the extreme ultraviolet ray can be radiated stably from the radiation source 41 while supplying the stannane gas from the tank 1 to the extreme ultraviolet ray radiation source 41 through the supply line L1.

In fact, in a stannane gas supply system shown in FIG. 1 with the controlling device 6 with the set pressure of 50 to 300 Torr, having the low pressure mass flow controller LMSFC with the flow rate controllable pressure range of 50 to 300 Torr provided in the stannane gas supply line L1, the temperature control of the tank 1 to be constantly cooled down at −80° C. by the freezing device 11 was carried out for 80 minutes by the pressure detecting device 5 and a controlling means (comprising the controlling device 6 and the room temperature air supply system 21 having the control valve Vc1), and thereafter the control was canceled for 10 minutes. The pressure of the stannane gas flowing in the supply line L1 at this time and the flow rate of the stannane gas by the low pressure mass flow controller LMSFC were measured. The results are shown in FIG. 2. The pressure and the flow rate of the stannane gas were a voltage equivalent value.

As it is apparent from FIG. 2, the pressure of the stannane gas flowing in the supply line L1 can be controlled in a narrow range by the temperature control of the tank 1 (mainly the stannane liquid) by the pressure detection device 5 and the controlling means so that the flow rate of the stannane gas can be provided constantly by the low pressure mass flow controller LMSFC.

FIG. 3 is a schematic chart showing a stannane gas supply system according to a second embodiment. In FIG. 3, the same numerals are applied to the same members explained in the first embodiment in FIG. 1 and explanation thereof is omitted.

In the stannane gas supply system according to the second embodiment, a controlling device 6 is connected with a compressing device 13 of a freezing device 11. The compressing device 13 adjusts the compression degree of the coolant circulating in a circulation line L2 by the control signal from the controlling device 6. According to the compression degree adjustment by the compressing device 13, the stannane cooling operation in a tank 1 at a winding part 12 of the circulation line L2 as an evaporating device can be controlled.

According to the configuration shown in FIG. 3, while supplying the stannane gas to the extreme ultraviolet ray radiation source 41 and radiating the extreme ultraviolet ray from the radiation source 41, in the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is outside the set pressure (for example 50 to 300 Torr), for example, a detection signal less than the lower limit of the set pressure is outputted from the pressure detecting device 5 to the controlling device 6 by cooling accompanied by the vaporization of the stannane liquid in the tank 1 as mentioned above, a control signal is outputted from the controlling device 6 to the compressing device 13 of the freezing device 11 so that the compression degree of the compressing device 13 is reduced according to the control signal. Thereby, the cooling temperature of the tank 1 in the freezing cycle (mainly the cooling temperature of the stannane liquid) is raised. According to the raise of the cooling temperature of the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is raised so as to be controlled into the set pressure of the controlling device 4, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSFC. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

On the other hand, in the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is higher than the upper limit of the set pressure (for example 50 to 300 Torr), a control signal for increasing the compression degree (for lowering the coolant temperature) is outputted to the compressing device 13 through the controlling device 6 so as to lower the cooling temperature of the tank 1 (mainly the stannane liquid) by the winding part 12 of the circulation line L2. By lowering the cooling temperature of the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is lowered so as to be controlled into the set pressure of the controlling device 6, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSFC. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

Therefore, according to the second embodiment, in the stannane gas supply system for supplying a stannane gas and a stannane liquid cooled down to a stable temperature without decomposition to the extreme ultraviolet ray radiation source 41, by carrying out the temperature control of the tank 1 (mainly the stannane liquid) by the pressure detecting device 5 and the controlling means (comprising the controlling device 6 and the compressing device 13 of the freezing device 11), that is, the pressure control of the stannane gas supplied from the tank 1, the pressure of the stannane gas to be supplied to the stannane gas supply line L1 so as to flow can be provided in a pressure range to enable the flow rate control of the low pressure mass flow controller LMSFC, for example, 50 to 300 Torr. Therefore, the stannane gas flowing in the supply line L1 can be supplied to the extreme ultraviolet ray radiation source 41 with the precise adjustment to the targeted flow rate by the low pressure mass flow controller LMSFC. As a result, the extreme ultraviolet ray can be radiated stably from the radiation source 41 while supplying the stannane gas from the tank 1 to the extreme ultraviolet ray radiation source 41 through the supply line L1.

FIG. 4 is a schematic chart showing a stannane gas supply system according to a third embodiment. In FIG. 4, the same numerals are applied to the same members explained in the first embodiment in FIG. 1 and explanation thereof is omitted.

A liquid nitrogen supply system 31 as the cooing means comprises a liquid nitrogen tank 32. A liquid nitrogen supply line L4 has its one end connected with the liquid nitrogen tank 32 and the other end passing through the outside housing 4 and the inside housing 2, and comprises a cooling winding part 33 for winding and cooling the tank 1 for storing a mixture of the stannane liquid and the stannane gas at the through part of the inside housing 2. The liquid nitrogen supply line L4 is provided with a control valve Vc2 for the opening degree adjustment by a control signal from the controlling device 6. The liquid nitrogen supply system 31 has the liquid nitrogen supply amount adjustment to the liquid nitrogen supply line L4 by the opening degree adjustment of the control valve Vc2 so as to control the stannane cooling operation in the tank 1 in the cooling winding part 33 of the supply line L4.

According to the configuration shown in FIG. 4, while supplying the stannane gas to the extreme ultraviolet ray radiation source 41 and radiating the extreme ultraviolet ray from the radiation source 41, in the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is outside the set pressure (for example 50 to 300 Torr), for example, a detection signal less than the lower limit of the set pressure is outputted from the pressure detecting device 5 to the controlling device 6 by cooling accompanied by the vaporization of the stannane liquid in the tank 1 as mentioned above, a control signal is outputted from the controlling device 6 to the control valve Vc2 of the liquid nitrogen supply system 31 so that the opening degree of the control valve Vc2 is reduced according to the control signal. Thereby, the cooling temperature of the tank 1 (mainly the stannane liquid) is raised by reducing the liquid nitrogen amount supplied to the cooing winding part 33 through the supply line L4 from the liquid nitrogen tank 32. According to the raise of the cooling temperature of the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is raised so as to be controlled into the set pressure of the controlling device 6, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSFC. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

On the other hand, in the case the pressure detection value signal outputted to the controlling device 6 from the pressure detecting device 5 is higher than the upper limit of the set pressure (for example 50 to 300 Torr), a control signal for increasing the opening degree of the control valve Vc2 of the liquid nitrogen supply system 31 (for increasing the liquid nitrogen supply amount) is outputted to the control valve Vc2 through the controlling device 6 so as to lower the cooling temperature of the tank 1 (mainly the stannane liquid) by the cooling winding part 32 of the liquid nitrogen supply line L4. By lowering the cooling temperature of the tank 1, from the exponentially proportional relationship between the temperature of the stannane liquid and the pressure of the stannane gas mentioned above, the pressure of the stannane gas supplied to the stannane gas supply line L1 is lowered so as to be controlled into the set pressure of the controlling device 4, that is, into the pressure range of 50 to 300 Torr to enable the flow rate control of the low pressure mass flow controller LMSFC. As a result, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 with the precise flow rate adjustment by the low pressure mass flow controller LMSFC provided in the supply line L1 so as to enable the stable radiation of the extreme ultraviolet ray continuously from the extreme ultraviolet ray radiation source 41.

Therefore, according to the third embodiment, in the stannane gas supply system for supplying a stannane gas and a stannane liquid cooled down to a stable temperature without decomposition to the extreme ultraviolet ray radiation source 41, by carrying out the temperature control of the tank 1 (mainly the stannane liquid) by the pressure detecting device 5 and the controlling means (comprising the controlling device 5 and the control valve Vc2 of the liquid nitrogen supply system 31), that is, the pressure control of the stannane gas supplied from the tank 1 for storing a mixture of the stannane liquid and the stannane gas, as it is explained in the first embodiment, the pressure of the stannane gas to be supplied to the stannane gas supply line L1 so as to flow can be provided in a pressure range to enable the flow rate control of the low pressure mass flow controller LMSFC, for example, 50 to 300 Torr. Therefore, the stannane gas flowing in the supply line L1 can be supplied to the extreme ultraviolet ray radiation source 41 with the precise adjustment to the targeted flow rate by the low pressure mass flow controller LMSFC. As a result, the extreme ultraviolet ray can be radiated stably from the radiation source 41 while supplying the stannane gas from the tank 1 to the extreme ultraviolet ray radiation source 41 through the supply line L1.

Although the tank 1 for storing a mixture of the stannane liquid and the stannane gas was cooled down by the liquid nitrogen from the liquid nitrogen tank 32 in the third embodiment, a sealed container (for example a tank) storing a low temperature liquefied gas such as a liquid helium, a liquid argon and a liquid carbon dioxide may be used instead of the liquid nitrogen tank for cooling down the stannane in the tank 1 by the low temperature liquefied gas such as a liquid helium, a liquid argon and a liquid carbon dioxide.

Moreover, although a low pressure mass flow controller having the flow rate controllable pressure range of 50 to 300 Torr was used in the first to third embodiments, a low pressure mass flow controller capable of controlling the flow rate at a pressure lower than this pressure range may be used as well.

Furthermore, in the first to third embodiments, by branching an exhaust line having a switching valve from the stannane gas supply line L1 part between the low pressure mass flow controller LMSFC and the switching valve V1, the stannane may be exhausted from the exhaust line until the stannane gas supply pressure is provided stably at a purposed value in the stannane gas supply initial stage from the tank 1 for storing a mixture of the stannane liquid and the stannane gas. That is, while the stannane gas supply pressure is outside the purposed value, the stannane gas is not supplied to the extreme ultraviolet ray radiation source 41, and when the supply pressure is stabilized, the stannane gas is supplied to the extreme ultraviolet ray radiation source 41 for driving the radiation source 41 and radiating the extreme ultraviolet ray.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic chart showing a stannane gas supply system according to a first embodiment.

FIG. 2 is a graph showing the stannane gas pressure flowing in the supply line L1 after having the temperature control of the tank 1 for 80 minutes and thereafter canceling the control for 10 minutes and the stannane gas flow speed by the low pressure mass flow controller LMSFC.

FIG. 3 is a schematic chart showing a stannane gas supply system according to a second embodiment.

FIG. 4 is a schematic chart showing a stannane gas supply system according to a third embodiment. 

1. A stannane gas supply system which supplies a stannane gas to an extreme ultraviolet ray radiation source, characterized by comprising: a) a sealed container which stores a mixture of a stannane liquid and a stannane gas, connected with the extreme ultraviolet ray radiation source via a pipe; b) cooling means for cooling the sealed container to a temperature lower than −60° C.; c) a low pressure mass flow controller provided in the pipe; d) a pressure detecting device which is mounted in the pipe portion disposed between the sealed container and the low pressure mass flow controller, and which detects the pressure of the stannane gas in the pipe portion; and e) controlling means for controlling the cooling degree of the sealed container by the cooling means based on the pressure detection value by the pressure detecting device.
 2. The stannane gas supply system of claim 1, wherein the low pressure mass flow controller is capable of controlling the flow rate of the stannane gas in a pressure range of 50 to 300 Torr.
 3. The stannane gas supply system of claim 1, wherein the cooling means comprises a circulation pipe for circulating a coolant, a compressing device, a condensing device, an expansion valve and an evaporating device provided in the coolant flow direction in the circulation pipe, and the evaporating device comprises a freezing device as a winding part of the circulation pipe for winding around the sealed container.
 4. The stannane gas supply system of claim 3, wherein the controlling means comprises: a heated gas supply system having a housing which stores the sealed container, a heated gas supply pipe which supplies a gas of a temperature higher than the cooling temperature of the sealed container in the freezing device into the housing, and a control valve provided in the pipe; and a controlling device to which a pressure detection value signal from the pressure detecting device is inputted, and which adjusts the opening degree of the control valve of the heated gas supply system based on the inputted signal.
 5. The stannane gas supply system of claim 3, wherein the controlling means comprises a controlling device to which a pressure detection value signal from the pressure detecting device is inputted, and which adjusts the compression degree of the coolant by the compressing device of the freezing device based on the inputted signal.
 6. The stannane gas supply system of claim 1, wherein the cooling means is a cooling liquid supply system comprising: a supply source of a cooling liquid of −60° C. or lower; a cooling liquid supply pipe connected with the supply source and having the winding part of the sealed container; and a control valve provided in the pipe.
 7. The stannane gas supply system of claim 6, wherein the controlling means comprises a controlling device to which a pressure detection value signal from the pressure detecting device is inputted, and which adjusts the opening degree of the control valve of the cooling liquid supply system based on the inputted signal.
 8. The stannane gas supply system of claim 6, wherein the cooling liquid of −60° C. or lower is a low temperature liquefied gas selected from the group consisting of a liquid nitrogen, a liquid helium, a liquid argon and a liquid carbon dioxide. 